Aerial imagery captured in 2019 and 2020 reveals the faint outline of a subcircular enclosure at Tonacooleen, measuring roughly 35 metres north to south and 32 metres east to west. It has been levelled, meaning its banks or walls no longer rise above the surrounding land, yet the differential in soil, moisture, or vegetation growth continues to betray its shape to a camera pointed downward from altitude.

Enclosures of this type, often the remains of a ringfort or a similar early medieval settlement boundary, were once a common feature of the Irish countryside. Thousands survive in varying states of preservation, but many more have been reduced by centuries of farming, ploughing, and land clearance to precisely this condition: present only as a crop mark or soil mark, noticed only when the light or the season is right. At Tonacooleen, a later field boundary running north to south cuts directly across the eastern sector of the enclosure, a small piece of agricultural history layered on top of an older one. The site was identified and reported by Jean-Charles Caillère, whose observation from satellite imagery brought it into the record.